The Performance Brake Kit ("PBK") concept is simple; improvements in design and construction combined with ideal rotor, caliper piston, and pad tuning will result in better braking and even a better-performing car. Whether it's a dedicated racecar or an enthusiast-driven street car, these benefits pay great dividends.

BMW brakes are not all that bad. Many racers get by quite satisfactorily with relatively small original brakes, so we can conclude that size is not entirely the issue. Nevertheless, the performance environment can stress the standard components in ways that diminish their effectiveness. After trying basic upgrades in pads and cooling, the next step is a "big brake kit". Done properly, a traditional "BBK" works great and solves the problems. However, the downsides include cost, wheel fitment, soft brake pedal, and incomplete systems that can affect the brake bias which will upset the handling of the car and even increase braking distances.

Instead of a "BBK", the concept of a "PBK" is to increase the Performance capabilities of the components while also being easier to use and less-expensive to maintain:

¹ For many applications, only the front axle kit is updated with the PBK brake torque calculated for ideal brake bias with the original rear brakes.  For other applications, there are the  options of the front-only PBK or a complete up-rated 4-wheel BBK

Calipers

The heart of the system is the race-developed calipers from Wilwood, the product of nearly 30 years of racing in every venue imaginable from SCCA Improved classes to the rigors of the NASCAR superspeedways. Depending on the BMW application, either a 4-piston forged Superlite or 6-piston Superlite caliper is used. Every version used is the latest premiere variant with piston sizes chosen to maintain excellent front/rear brake bias with the rotor size selected, and to maintain a firm pedal feel. The significant benefits include:

• stiffness exceeding the OEM iron and other aftermarket cast aluminum calipers, resulting in even pad wear and elimination of mushy brakes due to caliper "squirm" caused by worn guide pins.
• easy pad changes due to top-loading caliper design.
• extremely light weight, approximately half of the cast iron BMW caliper.
• affordable race pads available from every major manufacturer, often 1/2 the cost of BMW-fitment pads.
• available in either black or red.

Rotors

Rotors are a critical part of the brake system's energy dissipation cycle. The UUC Stage2 and Stage3 kits use the rotor fitment from the E46 M3. Benefits include:

• approximately 8%-15%* greater diameter for more surface area.
• up to 50%* greater thickness for larger interior cooling vents.
• affordable standard 1-piece design or genuine BMW Motorsport "floating" rotors for with separate center hat to keep heat out of the wheel bearing and to allow distortion-free heat expansion.
• choice of slotted or cross-drilled.
  

Pads

The "business end" of any brake setup is the specific friction material used, which determines the final characteristics of response curve, heat range, longevity, and a variety of other characteristics including fine-tuning of brake bias through different front/rear compounds. Every major pad manufacturer offers their entire line of racing compounds and several street compounds for the Wilwood Dynalite and Superlite calipers, including but not limited to:

Wilwood PolyMatrix
Carbotech
Cobalt Friction
EBC
Hawk
KFP Magnum (formerly Cool Carbon)
Pagid Racing
Performance Friction
Porterfield

Brackets, hardware, and brake lines

Strong steel bracketry is a minor weight concession that ensures durability and strength. All mounting hardware is the appropriate metric or SAE size, and stainless steel brake lines are DOT-compliant.